I would say no. My 900 has served me well. That said, it is pretty clear that new apps will be almost solely for WP8 phones. While at the second it isn't bad yet, a few months will change things. The 920 is being sold off contract for a really good price so look there.

I wouldn't go that far. A Windows 7.5 phone will still get the update to 7.8 and as of right now it can use any of the 100,000+ apps in the marketplace.

We've all be using and are still using WP7 phones and they will continue to be perfectly serviceable for anyone who doesn't demand the latest and greatest.

As far as WP7 being "dead" it's not just yet. It's going to be a while yet until there's a big selection of WP8 only apps that everyone's going to be lusting after. I'd say maybe the middle of next year if Microsoft is on top of things. Until then there will be little difference between a WP8 and WP7 phone aside from resolution and new OS features.

I just wouldn't recommend buying a new WP7 phone at this point, that's all. If money is tight, you probably don't want a $100/mo plan with AT&T or Verizon etc anyway so saving $ by getting a 99 cent Lumia 900 makes little sense.

For someone on a tight budget, I'd say wait for T-mo to get the Lumia 810 and buy one of those with a $50-60 Monthly 4G plan.